/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.optimize;

import proguard.classfile.*;
import proguard.classfile.util.*;
import proguard.classfile.visitor.MemberVisitor;
import proguard.evaluation.value.Value;
import proguard.optimize.evaluation.StoringInvocationUnit;

/**
 * This <code>MemberVisitor</code> delegates its visits to program methods to another given <code>MemberVisitor</code>,
 * for each method parameter that has been marked as constant.
 *
 * @see StoringInvocationUnit
 * @author Eric Lafortune
 */
public class ConstantParameterFilter extends SimplifiedVisitor implements MemberVisitor {
    private final MemberVisitor constantParameterVisitor;

    /**
     * Creates a new ConstantParameterFilter.
     * 
     * @param constantParameterVisitor the <code>MemberVisitor</code> to which visits will be delegated.
     */
    public ConstantParameterFilter(MemberVisitor constantParameterVisitor) {
        this.constantParameterVisitor = constantParameterVisitor;
    }

    // Implementations for MemberVisitor.

    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod) {
        // All parameters of non-static methods are shifted by one in the local
        // variable frame.
        int firstParameterIndex = (programMethod.getAccessFlags() & ClassConstants.ACC_STATIC) != 0 ? 0 : 1;

        int parameterCount = ClassUtil.internalMethodParameterCount(programMethod.getDescriptor(programClass));

        for (int index = firstParameterIndex; index < parameterCount; index++) {
            Value value = StoringInvocationUnit.getMethodParameterValue(programMethod, index);
            if (value != null && value.isParticular()) {
                constantParameterVisitor.visitProgramMethod(programClass, programMethod);
            }
        }
    }
}